in progress ...

command.rkt

@@ -5,8 +5,8 @@
 
 (require (for-syntax sugar "world.rkt"))
 
-(define-syntax (handle-pollen-command syntax-context)
-  (datum->syntax syntax-context
+(define-syntax (handle-pollen-command stx)
+  (datum->syntax stx
                  (let* ([args (current-command-line-arguments)]
                         [arg (if (> (len args) 0) (get args 0) "")])
                    (display (format "~a: " COMMAND_FILE))
@@ -65,3 +65,4 @@ polcom [filename] (renders individual file)")]
                                  `(displayln (format "No command defined for '~a'" ,arg))))]))))
 
 (handle-pollen-command)
+

debug.rkt

@@ -1,8 +1,8 @@
 #lang racket/base
 (require racket/date racket/string)
-(require sugar/debug)
+(require sugar/debug sugar/define)
 
-(provide message make-datestamp make-timestamp display-stack-trace (all-from-out sugar/debug))
+(provide  (all-from-out sugar/debug))
 
 ; todo: contracts, tests, docs
 
@@ -25,7 +25,7 @@
       str
       (string-append (make-string (- count (string-length str)) #\0) str)))
 
-(define (make-datestamp)
+(define+provide (make-datestamp)
   (define date (current-date))
   (define date-fields (map (λ(x) (zero-fill x 2)) 
                            (list
@@ -35,7 +35,7 @@
                             )))
   (string-join date-fields "-"))
 
-(define (make-timestamp)  
+(define+provide (make-timestamp)  
   (define date (current-date))
   (define time-fields (map (λ(x) (zero-fill x 2)) 
                            (list
@@ -57,14 +57,12 @@
 
 
 ;; todo: consolidate these two message functions
-(define (basic-message . items)
+(define+provide (basic-message . items)
   (displayln (string-join `(,@(map (λ(x)(if (string? x) x (format "~v" x))) items))) (current-error-port)))
 
-(define (message . items)
+(define+provide (message . items)
   (displayln (string-join `(,(make-debug-timestamp) ,@(map (λ(x)(if (string? x) x (format "~v" x))) items))) (current-error-port)))
 
-
-
 (define (exn+stack->string exn)
   (string-append 
    (string-append "Exception: " (exn-message exn)) 

decode.rkt

@@ -1,31 +1,17 @@
 #lang racket/base
 (require racket/contract racket/list racket/string racket/match)
 (require (only-in xml xexpr/c))
-(require "tools.rkt" "predicates.rkt")
+(require "tools.rkt" "predicates.rkt" sugar tagged-xexpr)
 
 (module+ test (require rackunit))
 
 (provide (except-out (all-defined-out) decode register-block-tag))
 
-(provide (contract-out
-          [decode ((xexpr/c) ;; use xexpr/c for contract on nx because it gives better error messages
-                   
-                   ;; todo: how to write more specific contracts for these procedures?
-                   ;; e.g., string-proc should be restricted to procs that accept a string as input
-                   ;; and return a string as output
-                   (#:exclude-xexpr-tags list?
-                                         #:xexpr-tag-proc procedure?
-                                         #:xexpr-attr-proc procedure?
-                                         #:xexpr-elements-proc procedure?
-                                         #:block-xexpr-proc procedure?
-                                         #:inline-xexpr-proc procedure?
-                                         #:string-proc procedure?)
-                   . ->* . tagged-xexpr?)]
-          [register-block-tag (symbol? . -> . void?)]))
 
 ;; add a block tag to the list
 ;; this function is among the predicates because it alters a predicate globally.
-(define (register-block-tag tag)
+(define+provide/contract (register-block-tag tag)
+  (symbol? . -> . void?)
   (append-block-tag tag))
 
 (module+ test
@@ -33,7 +19,7 @@
 
 
 ;; decoder wireframe
-(define (decode nx
+(define+provide/contract (decode nx
                 #:exclude-xexpr-tags [excluded-xexpr-tags '()]
                 #:xexpr-tag-proc [xexpr-tag-proc (λ(x)x)]
                 #:xexpr-attr-proc [xexpr-attr-proc (λ(x)x)]
@@ -41,7 +27,19 @@
                 #:block-xexpr-proc [block-xexpr-proc (λ(x)x)]
                 #:inline-xexpr-proc [inline-xexpr-proc (λ(x)x)]
                 #:string-proc [string-proc (λ(x)x)])
-  
+  ((xexpr/c) ;; use xexpr/c for contract on nx because it gives better error messages
+                   
+                   ;; todo: how to write more specific contracts for these procedures?
+                   ;; e.g., string-proc should be restricted to procs that accept a string as input
+                   ;; and return a string as output
+                   (#:exclude-xexpr-tags list?
+                                         #:xexpr-tag-proc procedure?
+                                         #:xexpr-attr-proc procedure?
+                                         #:xexpr-elements-proc procedure?
+                                         #:block-xexpr-proc procedure?
+                                         #:inline-xexpr-proc procedure?
+                                         #:string-proc procedure?)
+                   . ->* . tagged-xexpr?)
   (when (not (tagged-xexpr? nx))
     (error (format "decode: ~v not a full tagged-xexpr" nx)))
   

file-tools.rkt

@@ -3,8 +3,6 @@
 (require (only-in racket/path filename-extension))
 (require "world.rkt" sugar)
 
-(module+ test (require rackunit))
-
 ;; for files like svg that are not source in pollen terms,
 ;; but have a textual representation separate from their display.
 (define+provide/contract (sourceish? x)

main-helper.rkt

@@ -1,5 +1,5 @@
 #lang racket/base
-(require (for-syntax racket/base pollen/tools))
+(require (for-syntax racket/base pollen/tools sugar))
 
 (require racket/contract/region)
 
@@ -54,7 +54,7 @@
                       ;; so raises possibility of inconsistent values.
                       ;; Whereas the complete path is unambiguous,
                       ;; and can be made relative by the caller (or otherwise altered).
-                      (->string hp)))))
+                      ((bound/c ->string) hp)))))
 
 
 ; Second step: apply a separate syntax transform to the identifier itself

main-imports.rkt

@@ -8,10 +8,14 @@
          pollen/tools 
          pollen/main-helper
          pollen/top
+         tagged-xexpr
+         sugar
          (only-in pollen/ptree ptree-source-decode path->pnode ptree?))
 
 (provide (all-from-out racket/list
                        pollen/tools 
                        pollen/main-helper
                        pollen/top
+                       tagged-xexpr
+                       sugar
                        pollen/ptree))

main-preproc-imports.rkt

@@ -5,12 +5,10 @@
 ;; and cached for the benefit of the render eval function.
 
 (require pollen/top
-         (only-in sugar ->list)
-         (only-in pollen/tools trim)
+         (only-in sugar ->list ->string trim)
          (only-in pollen/predicates whitespace?))
 
 (provide (all-from-out
           pollen/top
           sugar
-          pollen/tools
           pollen/predicates))

main-preproc.rkt

@@ -1,6 +1,6 @@
 #lang racket/base
 
-(require "main-preproc-imports.rkt" sugar)
+(require "main-preproc-imports.rkt")
 (provide (except-out (all-from-out racket/base) #%module-begin)
          (rename-out [module-begin #%module-begin]))
 

main.rkt

@@ -26,7 +26,7 @@
      ;; and why doesn't this work:
      ;;     (require pollen/main-imports)
      ;;     (provide (all-from-out pollen/main-imports))
-     (require pollen/tools pollen/main-helper pollen/top pollen/ptree)
+     (require pollen/tools pollen/main-helper pollen/top pollen/ptree sugar tagged-xexpr)
      (require-and-provide-extras) ; brings in the project require files
      
      expr ... ; body of module  
@@ -57,7 +57,7 @@
    
    ;; split out the metas now (in raw form)
    (define-values (metas-raw main-raw) 
-     (split-tag-from-xexpr 'meta (make-tagged-xexpr 'irrelevant-tag empty all-elements)))
+     ((bound/c split-tag-from-xexpr) 'meta (make-tagged-xexpr 'irrelevant-tag empty all-elements)))
    
    (define metas (make-meta-hash metas-raw))
    
@@ -72,7 +72,7 @@
    ;; Because if it's overridden to something other than *.ptree, 
    ;; ptree processing will fail.
    ;; This defeats rule that ptree file suffix triggers ptree decoding.
-   (define here-is-ptree? ((bound/c ptree-source?) (->path inner-here-path)))
+   (define here-is-ptree? ((bound/c ptree-source?) ((bound/c ->path) inner-here-path)))
    
    (define main (apply (if here-is-ptree?
                            ;; ptree source files will go this way,
@@ -81,7 +81,7 @@
                            ;; Root is treated as a function. 
                            ;; If it's not defined elsewhere, 
                            ;; it just hits #%top and becomes a tagged-xexpr.
-                           root) (tagged-xexpr-elements main-raw)))
+                           root) ((bound/c tagged-xexpr-elements) main-raw)))
    
    
    (provide main metas here

predicates.rkt

@@ -1,171 +1,34 @@
 #lang racket/base
-(require racket/contract racket/match racket/list xml racket/set)
-(require css-tools/html)
-(require "world.rkt" sugar "file-tools.rkt" "debug.rkt")
-
-(module+ test (require rackunit))
-
-
-(provide (all-defined-out)
-         (all-from-out "file-tools.rkt"))
-
-
-
-;; is it an xexpr tag?
-(define/contract (xexpr-tag? x)
-  (any/c . -> . boolean?)
-  (symbol? x)) 
-
-;; is it an xexpr attributes?
-(define/contract (xexpr-attr? x)
-  (any/c . -> . boolean?)
-  (match x
-    ; list of symbol + string pairs
-    [(list (list (? symbol? key) (? string? value)) ...) #t]
-    [else #f]))
-
-(module+ test  
-  (check-true (xexpr-attr? empty))
-  (check-true (xexpr-attr? '((key "value"))))
-  (check-true (xexpr-attr? '((key "value") (foo "bar"))))
-  (check-false (xexpr-attr? '((key "value") "foo" "bar"))) ; content, not attr
-  (check-false (xexpr-attr? '(key "value"))) ; not a nested list
-  (check-false (xexpr-attr? '(("key" "value")))) ; two strings
-  (check-false (xexpr-attr? '((key value))))) ; two symbols
-
-
-;; is it xexpr content?
-(define/contract (xexpr-element? x)
-  (any/c . -> . boolean?)
-  (or (string? x) (tagged-xexpr? x)))
-
-;; Not a great idea to use "plural" (i.e. listlike) contracts.
-;; Instead of foobars? use (listof foobar?) as contract
-;; Reason is that listof will show you the specific element that fails
-;; whereas foobars? will just announce the result for the whole list.
-;; Since contracts are intended to tell you why your input is defective,
-;; the (listof foobar?) behavior is better.
-;; outside of contracts, instead of testing (foobars? list),
-;; test (andmap foobar? list)
-
-(define/contract (xexpr-elements? x)
-  (any/c . -> . boolean?)
-  (match x
-    ;; this is more strict than xexpr definition in xml module
-    ;; don't allow symbols or numbers to be part of content
-    [(list elem ...) (andmap xexpr-element? elem)]
-    [else #f]))
-
-(module+ test  
-  (check-true (xexpr-elements? '("p" "foo" "123")))
-  (check-false (xexpr-elements? "foo")) ; not a list
-  (check-false (xexpr-elements? '("p" "foo" 123))) ; includes number
-  (check-false (xexpr-elements? '(p "foo" "123"))) ; includes symbol
-  (check-false (xexpr-elements? '(((key "value")) "foo" "bar"))) ; includes attr
-  (check-false (xexpr-elements? '("foo" "bar" ((key "value")))))) ; malformed
-
-
-;; is it a named x-expression?
-;; todo: rewrite this recurively so errors can be pinpointed (for debugging)
-(define/contract (tagged-xexpr? x)
-  (any/c . -> . boolean?)
-  (and (xexpr? x) ; meets basic xexpr contract
-       (match x
-         [(list (? symbol? name) rest ...) ; is a list starting with a symbol
-          (or (andmap xexpr-element? rest) ; the rest is content or ...
-              (and (xexpr-attr? (car rest)) (andmap xexpr-element? (cdr rest))))] ; attr + content 
-         [else #f])))
-
-(module+ test  
-  (check-true (tagged-xexpr? '(p "foo" "bar")))
-  (check-true (tagged-xexpr? '(p ((key "value")) "foo" "bar")))
-  (check-false (tagged-xexpr? "foo")) ; not a list with symbol
-  (check-false (tagged-xexpr? '(p "foo" "bar" ((key "value"))))) ; malformed
-  (check-false (tagged-xexpr? '("p" "foo" "bar"))) ; no name
-  (check-false (tagged-xexpr? '(p 123)))) ; content is a number
+(require racket/contract racket/match racket/set)
+(require css-tools/html sugar tagged-xexpr)
+(require "world.rkt" "file-tools.rkt" "debug.rkt")
 
+(provide (all-from-out "file-tools.rkt"))
 
 ;; test for well-formed meta
-(define/contract (meta-xexpr? x)
+(define+provide/contract (meta-xexpr? x)
   (any/c . -> . boolean?)
   (match x
     [`(meta ,(? string? key) ,(? string? value)) #t]
     [else #f]))
 
-(module+ test
-  (check-true (meta-xexpr? '(meta "key" "value")))
-  (check-false (meta-xexpr? '(meta "key" "value" "foo")))
-  (check-false (meta-xexpr? '(meta))))
-
-
 ;; initial set of block tags: from html
 (define project-block-tags block-tags)
 
-(define/contract (append-block-tag tag)
+(define+provide/contract (append-block-tag tag)
   (xexpr-tag? . -> . void?)
   (set! project-block-tags (cons tag project-block-tags)))
 
 ;; is the tagged-xexpr a block element (as opposed to inline)
 ;; tags are inline unless they're registered as block tags.
-(define/contract (block-xexpr? x)
+(define+provide/contract (block-xexpr? x)
   (any/c . -> . boolean?)
   ;; (car x) = shorthand for tag of xexpr
   ((tagged-xexpr? x) . and . ((car x) . in? . project-block-tags)))
 
-(module+ test
-  (check-true (block-xexpr? '(p "foo")))
-  (check-true (block-xexpr? '(div "foo")))
-  (check-false (block-xexpr? '(em "foo")))
-  (check-false (block-xexpr? '(barfoo "foo"))))
-
-
-;; count incidence of elements in a list
-;; returns hash where key is element, value is incidence
-;; todo: move this? Ideally it would be in tools,
-;; but that would create a circular dependency.
-(define/contract (count-incidence x)
-  (list? . -> . hash?)
-  (define counter (make-hash))
-  (for ([item (flatten x)]) 
-    (hash-set! counter item (add1 (hash-ref counter item 0))))
-  counter)
-
-(module+ test
-  (check-equal? (hash-ref (count-incidence '(a b c d b c)) 'b) 2)
-  (check-equal? (hash-ref (count-incidence '(a b c d b c)) 'a) 1))
-
-
-(define/contract (members-unique? x)
-  (any/c . -> . boolean?)
-  (cond 
-    [(list? x) (= (len (apply set x)) (len x))]
-    [(vector? x) (members-unique? (->list x))]
-    [(string? x) (members-unique? (string->list x))]
-    [else #t]))
-
-(define/contract (members-unique?/error x)
-  (any/c . -> . boolean?)
-  (define result (members-unique? x))
-  (if (not result)
-      (let* ([duplicate-keys (filter-not empty? (hash-map (count-incidence x) 
-                                                          (λ(k v) (if (> v 1) k '()))))])
-        (error (string-append (if (= (len duplicate-keys) 1) 
-                                  "Item isn’t"
-                                  "Items aren’t") " unique:") duplicate-keys))
-      result))
-
-(module+ test
-  (check-true (members-unique? '(1 2 3)))
-  (check-false (members-unique? '(1 2 2)))
-  (check-true (members-unique? (->vector '(1 2 3))))
-  (check-false (members-unique? (->vector '(1 2 2))))
-  (check-true (members-unique? "fob"))
-  (check-false (members-unique? "foo")))
-
-
 
 ;; recursive whitespace test
-(define/contract (whitespace? x)
+(define+provide/contract (whitespace? x)
   (any/c . -> . boolean?)
   (cond
     [(or (vector? x) (list? x) (set? x)) (andmap whitespace? (->list x))]
@@ -173,14 +36,6 @@
     [(or (symbol? x) (string? x)) (->boolean (regexp-match #px"^\\s+$" (->string x)))]
     [else #f]))
 
-(module+ test
-  (check-true (whitespace? " "))
-  (check-false (whitespace? "foo"))
-  (check-false (whitespace? 'foo))
-  (check-false (whitespace? #\Ø))
-  (check-false (whitespace? " ")) ; a nonbreaking space. todo: why is this so?
-  (check-true (whitespace? "\n \n"))
-  (check-true (whitespace? (list "\n" " " "\n")))
-  (check-true (whitespace? (list "\n" " " "\n" (list "\n" "\n")))))
+
 
 

ptree.rkt

@@ -1,6 +1,6 @@
 #lang racket/base
-(require racket/contract racket/match xml/path racket/bool racket/rerequire)
-(require "tools.rkt" "world.rkt" "debug.rkt" "decode.rkt")
+(require racket/contract racket/match racket/path xml/path racket/bool racket/rerequire)
+(require "tools.rkt" "world.rkt" "debug.rkt" "decode.rkt" sugar tagged-xexpr)
 
 (module+ test (require rackunit))
 
@@ -8,7 +8,8 @@
 
 (define/contract (pnode? x)
   (any/c . -> . boolean?)
-  (and (stringish? x) (not (whitespace? (->string x)))))
+  (try (not (whitespace? (->string x)))
+       (except [exn:fail? (λ(e) #f)])))
 
 (define/contract (pnode?/error x)
   (any/c . -> . boolean?)

render.rkt

@@ -1,6 +1,8 @@
 #lang racket/base
-(require racket/port racket/file racket/rerequire racket/contract)
-(require "world.rkt" "tools.rkt" "template.rkt")
+(require racket/port racket/file racket/rerequire racket/contract racket/path)
+;(require "world.rkt" )
+
+;;todo: why is pollen/top operating in this file?
 
 (module+ test (require rackunit))
 

server-routes.rkt

@@ -5,7 +5,7 @@
 (require web-server/http/request-structs)
 (require web-server/http/response-structs)
 (require 2htdp/image)
-(require "world.rkt" "render.rkt" sugar "predicates.rkt" "debug.rkt" "ptree.rkt")
+(require "world.rkt" "render.rkt" sugar tagged-xexpr "predicates.rkt" "debug.rkt" "ptree.rkt")
 
 (module+ test (require rackunit))
 

template.rkt

@@ -1,11 +1,12 @@
 #lang racket/base
 (require racket/contract racket/string xml xml/path racket/bool)
-(require "tools.rkt" "ptree.rkt" sugar/scribble)
+(require "tools.rkt" "ptree.rkt" sugar/scribble sugar/coerce sugar tagged-xexpr)
 
 ;; setup for test cases
 (module+ test (require rackunit racket/path))
 
 (provide (all-defined-out))
+(provide (all-from-out sugar/scribble sugar/coerce))
 
 ;; todo: better fallback template
 
@@ -35,11 +36,11 @@
     [(has-decoder-source? x) (dynamic-require (->decoder-source-path x) 'main)]
     [(has-decoder-source? (pnode->url x)) (dynamic-require (->decoder-source-path (pnode->url x)) 'main)]))
 
-(module+ test
+#|(module+ test
   (check-equal? (put '(foo "bar")) '(foo "bar"))
   (check-equal? (put "tests/template/put.pd") 
                 '(root "\n" "\n" (em "One") " paragraph" "\n" "\n" "Another " (em "paragraph") "\n" "\n")))
-
+|#
 
 
 (define/contract (find query px)
@@ -47,12 +48,14 @@
   (define result (and px (or (find-in-metas px query) (find-in-main px query))))
   (and result (car result))) ;; return false or first element
 
+#|
 (module+ test 
   (parameterize ([current-directory "tests/template"])
     (check-false (find "nonexistent-key" "put"))
     (check-equal? (find "foo" "put") "bar")
     (check-equal? (find "em" "put") "One"))
   (check-equal? (find "foo" #f) #f))
+|#
 
 (define/contract (find-in-metas px key)
   (puttable-item? query-key? . -> . (or/c false? xexpr-elements?))
@@ -61,13 +64,13 @@
              [key (->string key)])
          (and (key . in? . metas ) (->list (get metas key))))))
 
-(module+ test
+#|(module+ test
   (parameterize ([current-directory "tests/template"])
     (check-equal? (find-in-metas "put" "foo") (list "bar"))
     (let* ([metas (dynamic-require (->decoder-source-path 'put) 'metas)]
            [here (find-in-metas 'put 'here)])     
       (check-equal? here (list "tests/template/put")))))
-
+|#
 
 (define/contract (find-in-main px query) 
   (puttable-item? (or/c query-key? (listof query-key?)) 
@@ -79,11 +82,12 @@
     ;; if results exist, send back xexpr as output
     (and (not (empty? results)) results)))
 
+#|
 (module+ test
   (parameterize ([current-directory "tests/template"])
     (check-false (find-in-main "put" "nonexistent-key"))
     (check-equal? (find-in-main "put" "em") (list "One" "paragraph"))))
-
+|#
 
 ;; turns input into xexpr-elements so they can be spliced into template
 ;; (as opposed to dropped in as a full tagged-xexpr)

tests/test-predicates.rkt

@@ -0,0 +1,40 @@
+#lang racket/base
+(require "../predicates.rkt" racket/list sugar)
+(module+ test (require rackunit))
+
+
+(module+ test
+  (check-true (meta-xexpr? '(meta "key" "value")))
+  (check-false (meta-xexpr? '(meta "key" "value" "foo")))
+  (check-false (meta-xexpr? '(meta))))
+
+
+(module+ test
+  (check-true (block-xexpr? '(p "foo")))
+  (check-true (block-xexpr? '(div "foo")))
+  (check-false (block-xexpr? '(em "foo")))
+  (check-false (block-xexpr? '(barfoo "foo"))))
+
+
+(module+ test
+  (check-equal? (hash-ref (count-incidence '(a b c d b c)) 'b) 2)
+  (check-equal? (hash-ref (count-incidence '(a b c d b c)) 'a) 1))
+
+(module+ test
+  (check-true (members-unique? '(1 2 3)))
+  (check-false (members-unique? '(1 2 2)))
+  (check-true (members-unique? (->vector '(1 2 3))))
+  (check-false (members-unique? (->vector '(1 2 2))))
+  (check-true (members-unique? "fob"))
+  (check-false (members-unique? "foo")))
+
+
+(module+ test
+  (check-true (whitespace? " "))
+  (check-false (whitespace? "foo"))
+  (check-false (whitespace? 'foo))
+  (check-false (whitespace? #\Ø))
+  (check-false (whitespace? " ")) ; a nonbreaking space. todo: why is this so?
+  (check-true (whitespace? "\n \n"))
+  (check-true (whitespace? (list "\n" " " "\n")))
+  (check-true (whitespace? (list "\n" " " "\n" (list "\n" "\n")))))

tools.rkt

@@ -1,19 +1,14 @@
 #lang racket/base
-(require racket/contract racket/match racket/path)
-(require (only-in racket/format ~a))
-(require racket/list)
-(require (only-in racket/string string-join))
-(require (only-in xml xexpr? xexpr/c))
-
-(require sugar "debug.rkt" "predicates.rkt" "world.rkt")
-(provide (all-defined-out) (all-from-out sugar "debug.rkt" "predicates.rkt" racket/list racket/path))
+(require racket/contract racket/list)
+(require tagged-xexpr sugar "debug.rkt" "predicates.rkt" "world.rkt")
+(provide (all-from-out "debug.rkt" "predicates.rkt" racket/list))
 
 ;; setup for test cases
 (module+ test (require rackunit))
 
 ;; list of all eligible requires in project require directory
-(define/contract (get-project-require-files)
-  (-> (or/c (listof complete-path?) boolean?))
+(define+provide/contract (get-project-require-files)
+  (-> (or/c #f (listof complete-path?)))
   (define extras-directory (build-path PROJECT_ROOT EXTRAS_DIR))
   (and (directory-exists? extras-directory)
        ;; #:build? option returns complete paths (instead of just file names)
@@ -21,215 +16,10 @@
          (and (not (empty? files)) files))))
 
 
-;; helper for comparison of values
-;; normal function won't work for this. Has to be syntax-rule
-(define-syntax-rule (values->list vs)
-  (call-with-values (λ() vs) list))
-
-
-;; convert list of alternating keys & values to attr
-;; todo: make contract. Which is somewhat complicated:
-;; list of items, made of xexpr-attr or even numbers of symbol/string pairs
-;; use splitf*-at with xexpr-attr? as test, then check lengths of resulting lists
-(define/contract (make-xexpr-attr . items)
-  (() #:rest (listof (λ(i) (or (xexpr-attr? i) (symbol? i) (string? i)))) . ->* . xexpr-attr?)
-  
-  ;; need this function to make sure that 'foo and "foo" are treated as the same hash key
-  (define (make-attr-list items)
-    (if (empty? items)
-        empty
-        (let ([key (->symbol (first items))]
-              [value (->string (second items))]
-              [rest (drop items 2)])
-          (append (list key value) (make-attr-list rest)))))
-  
-  ;; use flatten to splice xexpr-attrs into list
-  ;; use hash to ensure keys are unique (later values will overwrite earlier)
-  (define attr-hash (apply hash (make-attr-list (flatten items))))
-  `(,@(map (λ(k) (list k (get attr-hash k))) 
-           ;; sort needed for predictable results for unit tests
-           (sort (hash-keys attr-hash) (λ(a b) (string<? (->string a) (->string b)))))))
-
-(module+ test
-  (check-equal? (make-xexpr-attr 'foo "bar") '((foo "bar")))
-  (check-equal? (make-xexpr-attr "foo" 'bar) '((foo "bar")))
-  (check-equal? (make-xexpr-attr "foo" "bar" "goo" "gar") '((foo "bar")(goo "gar")))
-  (check-equal? (make-xexpr-attr (make-xexpr-attr "foo" "bar" "goo" "gar") "hee" "haw") 
-                '((foo "bar")(goo "gar")(hee "haw")))
-  (check-equal? (make-xexpr-attr '((foo "bar")(goo "gar")) "foo" "haw") '((foo "haw")(goo "gar"))))
-
-
-
-
-
-;; create tagged-xexpr from parts (opposite of break-tagged-xexpr)
-(define/contract (make-tagged-xexpr name [attr empty] [content empty])
-  ; xexpr/c provides a nicer error message,
-  ; but is not sufficient on its own (too permissive)
-  ((symbol?) (xexpr-attr? (listof xexpr-element?)) 
-             . ->* . tagged-xexpr?)
-  (filter-not empty? `(,name ,attr ,@content)))
-
-(module+ test
-  (check-equal? (make-tagged-xexpr 'p) '(p))
-  (check-equal? (make-tagged-xexpr 'p '((key "value"))) '(p ((key "value"))))
-  (check-equal? (make-tagged-xexpr 'p empty '("foo" "bar")) '(p "foo" "bar"))
-  (check-equal? (make-tagged-xexpr 'p '((key "value")) (list "foo" "bar")) 
-                '(p ((key "value")) "foo" "bar")))
-
-
-;; decompose tagged-xexpr into parts (opposite of make-tagged-xexpr)
-(define/contract (break-tagged-xexpr nx)
-  (tagged-xexpr? . -> . 
-                 (values symbol? xexpr-attr? (listof xexpr-element?)))
-  (match 
-      ; tagged-xexpr may or may not have attr
-      ; if not, add empty attr so that decomposition only handles one case
-      (match nx
-        [(list _ (? xexpr-attr?) _ ...) nx]
-        [else `(,(car nx) ,empty ,@(cdr nx))])
-    [(list tag attr content ...) (values tag attr content)]))
-
-(module+ test
-  (check-equal? (values->list (break-tagged-xexpr '(p))) 
-                (values->list (values 'p empty empty)))
-  (check-equal? (values->list (break-tagged-xexpr '(p "foo"))) 
-                (values->list (values 'p empty '("foo"))))
-  (check-equal? (values->list (break-tagged-xexpr '(p ((key "value"))))) 
-                (values->list (values 'p '((key "value")) empty)))
-  (check-equal? (values->list (break-tagged-xexpr '(p ((key "value")) "foo"))) 
-                (values->list (values 'p '((key "value")) '("foo")))))
-
-
-;; convenience functions to retrieve only one part of tagged-xexpr
-(define (tagged-xexpr-tag nx)
-  (tagged-xexpr? . -> . xexpr-tag?)
-  (define-values (tag attr content) (break-tagged-xexpr nx))
-  tag)
-
-(define (tagged-xexpr-attr nx)
-  (tagged-xexpr? . -> . xexpr-attr?)
-  (define-values (tag attr content) (break-tagged-xexpr nx))
-  attr)
-
-(define (tagged-xexpr-elements nx)
-  (tagged-xexpr? . -> . (listof xexpr-element?))
-  (define-values (tag attrt elements) (break-tagged-xexpr nx))
-  elements)
-
-(module+ test
-  (check-equal? (tagged-xexpr-tag '(p ((key "value"))"foo" "bar" (em "square"))) 'p)
-  (check-equal? (tagged-xexpr-attr '(p ((key "value"))"foo" "bar" (em "square"))) '((key "value")))
-  (check-equal? (tagged-xexpr-elements '(p ((key "value"))"foo" "bar" (em "square"))) 
-                '("foo" "bar" (em "square"))))
-
-
-;; remove all attr blocks (helper function)
-(define/contract (remove-attrs x)
-  (tagged-xexpr? . -> . tagged-xexpr?)
-  (match x
-    [(? tagged-xexpr?) (let-values ([(tag attr elements) (break-tagged-xexpr x)])
-                         (make-tagged-xexpr tag empty (remove-attrs elements)))]
-    [(? list?) (map remove-attrs x)]
-    [else x]))
-
-(module+ test
-  (check-equal? (remove-attrs '(p ((foo "bar")) "hi")) '(p "hi"))
-  (check-equal? (remove-attrs '(p ((foo "bar")) "hi" (p ((foo "bar")) "hi"))) '(p "hi" (p "hi"))))
-
-
-;; apply filter proc recursively
-(define/contract (filter-tree proc tree)
-  (procedure? list? . -> . list?)
-  (define (remove-empty x)
-    (cond
-      [(list? x) (filter-not empty? (map remove-empty x))]
-      [else x]))
-  
-  (define (filter-tree-inner proc x)
-    (cond
-      [(list? x) (map (λ(i) (filter-tree-inner proc i)) x)]
-      [else (if (proc x) x empty)]))
-  
-  (remove-empty (filter-tree-inner proc tree)))
-
-
-(module+ test
-  (check-equal? (filter-tree string? '(p)) empty)
-  (check-equal? (filter-tree string? '(p "foo" "bar")) '("foo" "bar"))
-  (check-equal? (filter-tree string? '(p "foo" (p "bar"))) '("foo" ("bar")))
-  (check-equal? (filter-tree (λ(i) (and (string? i) (equal? i "\n"))) '("\n" (foo "bar") "\n")) '("\n" "\n"))) 
-
-;; apply filter-not proc recursively
-(define/contract (filter-not-tree proc tree)
-  (procedure? list? . -> . list?)
-  (filter-tree (λ(i) (not (proc i))) tree))
-
-(module+ test
-  (check-equal? (filter-not-tree string? '(p)) '(p))
-  (check-equal? (filter-not-tree string? '(p "foo" "bar")) '(p))
-  (check-equal? (filter-not-tree string? '(p "foo" (p "bar"))) '(p (p)))
-  ;(check-equal? (filter-tree (λ(i) (and (tagged-xexpr? i) (equal? 'em (car i)))) '(p "foo" (em "bar"))) '(p "foo"))
-  )
-
-
-;; todo: doc this function
-(define/contract (map-tree proc tree)
-  (procedure? list? . -> . list?)
-  (cond 
-    [(list? tree) (map (λ(i) (map-tree proc i)) tree)]
-    [else (proc tree)]))
-
-(module+ test
-  (check-equal? (map-tree (λ(i) (if (number? i) (* 2 i) i)) '(p 1 2 3 (em 4 5))) '(p 2 4 6 (em 8 10)))
-  (check-equal? (map-tree (λ(i) (if (symbol? i) 'foo i)) '(p 1 2 3 (em 4 5))) '(foo 1 2 3 (foo 4 5))))
-
-
-(define/contract (map-xexpr-elements proc tx)
-  (procedure? tagged-xexpr? . -> . tagged-xexpr?)
-  (define-values (tag attr elements) (break-tagged-xexpr tx)) 
-  (make-tagged-xexpr tag attr (map proc elements)))
-
-(module+ test
-  (check-equal? (map-xexpr-elements (λ(x) (if (string? x) "boing" x))  
-                                    '(p "foo" "bar" (em "square"))) 
-                '(p "boing" "boing" (em "square"))))
-
-
-
-
-;; function to split tag out of tagged-xexpr
-(define/contract (split-tag-from-xexpr tag tx)
-  (xexpr-tag? tagged-xexpr? . -> . (values (listof xexpr-element?) tagged-xexpr? ))
-  (define matches '())
-  (define (extract-tag x)
-    (cond
-      [(and (tagged-xexpr? x) (equal? tag (car x)))
-       ; stash matched tag but return empty value
-       (begin
-         (set! matches (cons x matches))
-         empty)]
-      [(tagged-xexpr? x) (let-values([(tag attr body) (break-tagged-xexpr x)]) 
-                           (make-tagged-xexpr tag attr (extract-tag body)))]
-      [(xexpr-elements? x) (filter-not empty? (map extract-tag x))]
-      [else x]))
-  (define tx-extracted (extract-tag tx)) ;; do this first to fill matches
-  (values (reverse matches) tx-extracted)) 
-
-
-(module+ test
-  (define xx '(root (meta "foo" "bar") "hello" "world" (meta "foo2" "bar2") 
-                    (em "goodnight" "moon" (meta "foo3" "bar3"))))
-  
-  (check-equal? (values->list (split-tag-from-xexpr 'meta xx)) 
-                (list '((meta "foo" "bar") (meta "foo2" "bar2") (meta "foo3" "bar3")) 
-                      '(root "hello" "world" (em "goodnight" "moon")))))
-
-
 ;; convert list of meta tags to a hash for export from pollen document.
 ;; every meta is form (meta "key" "value") (enforced by contract)
 ;; later metas with the same name will override earlier ones.
-(define/contract (make-meta-hash mxs)
+(define+provide/contract (make-meta-hash mxs)
   ((listof meta-xexpr?) . -> . hash?)
   (apply hash (append-map tagged-xexpr-elements mxs)))